1. Field of the Invention
The present invention concerns reduced calorie spoonable dressings that exhibit freeze-thaw stability. More specifically, the invention relates to spoonable dressings wherein some or all of the blended salad oil has been replaced with a fatty acid-esterified propoxylated glycerin compositions having from about 3 to about 16 oxypropylene units per unit of glycerin wherein the ratio of total fatty acid carbon number to degree of fatty acid unsaturation (herein referred to as the (xe2x80x9cFACN:DU Ratioxe2x80x9d) is less than about 120, preferably less than about 90 for fatty acid esterified propoxylated glycerin compositions having unsaturated fatty acids or the ratio of a total fatty acid carbon number to propoxylation number (herein referred to as the xe2x80x9cFACN:PO Ratioxe2x80x9d) is less than about 6, preferably less than about 5, for fatty acid esterified propoxylated glycerin compositions that do not have unsaturated fatty acids. Replacement of the blended salad oil with these fatty acid-esterified propoxylated glycerin compositions provides the spoonable dressing with exemplary freeze-thaw stability.
2. Description of the Related Art
Conventional spoonable dressings, such as full fat mayonnaise, lack freeze-thaw stability. Dressings made with blended salad oil, such as soybean oils or other lipid based fats, will incur complete emulsion break after being frozen. The freeze-thaw characteristics of such dressings, like mayonnaises, are undesirable, for example, when storage and transportation occurs in climatic conditions wherein temperatures are below freezing. The lack of freeze-thaw stability of conventional dressings limits transportation and storage options available for full fat spoonable dressings. Conventional dressings, if frozen after a period of time, will separate when thawed thus rendering the dressing un-marketable.
It has now been found that certain fatty acid-esterified propoxylated glycerin compositions can be employed as a substitute replacement for some or all of the blended salad oil in spoonable dressings such as mayonnaise. The compositions have a bland flavor and the ability to form a stable emulsion. The use of fatty acid-esterified propoxylated glycerin compositions as a partial replacement for all or some of the fat surprisingly provides the dressing with freeze-thaw stability. The freeze-thaw stability of the dressings improves as increased amounts of blended salad oil is replaced with the fatty acid-esterified propoxylated glycerin compositions. The dressing comprising the fatty acid-esterified propoxylated glycerin compositions as full or partial replacement for blended salad oil has reduced calories compared to full fat dressings. Thus, fatty acid-esterified propoxylated glycerin compositions can be used to make fine tasting, premium quality spoonable dressings having smooth texture, good spreadability and reduced calories with freeze-thaw stability.
Since fats make up approximately forty percent of the diet and provide about twice the amount of calories per gram compared to proteins or carbohydrates, research efforts have focused on ways to produce low fat and no fat foods that provide the same functional and organoleptic properties as their full fat counterparts, but not the calories. These efforts have led to the development and utilization of carbohydrate and protein based fat extenders for non-heated applications (e.g. mayonnaise) and the development of lipid based fat replacers for both non-heated and heated applications. Drawbacks to the utilization of carbohydrate and protein based fat extenders, however, include potential flavor and taste problems, substandard texture and lack of xe2x80x9cfattyxe2x80x9d mouthfeel.
Fat replacement compositions which have been developed for use in low calorie fat containing foods are known. An early development employing sugar fatty acid esters is described in U.S. Pat. No. 3,600,186.
Low fat and no fat mayonnaise prepared with lipid based fat replacers are described in the art, and examples include acylated glycerides (U.S. Pat. No. 4,582,715), sucrose octaesters (U.S. Pat. No. 4,797,300), alkyl glycoside fatty acid polyesters (U.S. Pat. No. 4,840,815), polysiloxane oil (U.S. Pat. No. 4,983,413), cyclohexyl diol diesters (U.S. Pat. No. 5,006,351), long chain diol diesters (U.S. Pat. No. 5,008,126), amide ether derivatives (U.S. Pat. No. 5,063,075), complex linked esters (U.S. Pat. No. 5,064,678), alcohol amine esters (U.S. Pat. No. 5,093,142), amide linked fat mimetics (U.S. Pat. No. 5,139,807), acylated amino acid ester derivatives (U.S. Pat. No. 5,190,782), primary amide esters (U.S. Pat. No. 5,190,783) and fat mimetics having mineral core with fatty coating (U.S. Pat. No. 5,230,913). However, no mention has been made that the substitution of vegetable oil with these fat replacers in mayonnaise improves product quality or stability, including providing the mayonnaise with freeze-thaw stability. All of the low calorie fat replacement compositions discussed above have drawbacks either in the processes which employ them, or the flavor and mouthfeel characteristics of the finished reduced fat products.
Esterified propoxylated glycerin fat substitutes said to be resistant to gastrointestinal side effects are the subject of European Patent Application 0 571 291 A2. These fat substitutes generally have 3 to 20 oxypropylene units per equivalent of glycerine, a fatty acid acyl group content such that at least 40 mole percent of the acyl groups are derived from C20 to C24 saturated linear fatty acids and a solid fat index at 27xc2x0 C. of at least 30. There is no mention that use of these EPG compounds provide freeze thaw stability, and these EPG compositions do not uniformly meet the FACN:DU Ratio and FACN:PO Ratio which characterize the fatty acid-esterified propoxylated glycerin compositions useful for the freeze thaw dressings described herein.
Reduced calorie food compositions containing fat-type organoleptic ingredients are known wherein an esterified epoxide-extended polyol is employed as a full or partial replacement for vegetable oils and fats. Fat substitutes of this type are disclosed in U.S. Pat. No. 4,861,613 to White et al. (referred to herein as xe2x80x9cWhitexe2x80x9d and incorporated by reference herein in its entirety).
An application of the assignee of the invention involving the replacement of conventional fat in nut butters with fatty acid-esterified propoxylated glycerin, Low Calorie Nut Butters and Processes for their Production, Ser. No. 09/466,471, filed Dec. 17, 1999, is currently pending. An application of the assignee concerning partially digestible fatty acid-esterified propoxylated glycerin compositions is also pending, Reduced Calorie Fat Mimetics with an Average Number of Oxyalkylene Groups per Molecule of No More than Five, Ser. No. 09/333,546 filed Jun. 15, 1999. These applications do not involve dressing preparations or the effect of fatty acid-esterified propoxylated glycerin compositions on freeze-thaw characteristics.
In the present specification and claims, all parts and percentages are by weight unless otherwise specified.
The fatty acid-esterified propoxylated glycerin compositions (sometimes referred to herein as xe2x80x9cEPGxe2x80x9d in the singular form and as xe2x80x9cEPGsxe2x80x9d in the plural form) are made by incorporating propylene oxide (sometimes referred to herein as xe2x80x9coxypropylenexe2x80x9d or xe2x80x9cPOxe2x80x9d) groups into a typical triglyceride fat as described in White. The average number of PO groups which are incorporated into a triglyceride is called the propoxylation number. The melting profile and other characteristics of the composition can be modified by adjusting the propoxylation number of a triglyceride, combining (i.e., employing as ingredients in a recipe) two or more different EPGs (i.e., having different propoxylation numbers) with the same fatty acid composition, combining two or more EPGs having different fatty acid compositions and having the same or different propoxylation numbers, and any combination thereof which provides the desired melting profile characteristics.
The invention exhibits freeze-thaw stability, that is the emulsion does not experience complete emulsion break upon thawing after a period of being continuously frozen, superior to that of conventional spoonable dressings made with blended salad oil. EPG compositions with propoxylation numbers from about 3 to about 16 and having unsaturated fatty acids with a FACN:DU Ratio of less than about 120, preferably less than about 90, or EPG that does not have unsaturated fatty acids with a FACN:PO Ratio of less than about 6, preferably less than about 5, are used as full or partial replacement of conventional oil in a dressing preparation. Spoonable dressings prepared with these EPGs demonstrate only slight oil separation upon thawing after being frozen for about 24 days. In comparison, however, conventional mayonnaise formulations prepared with blended salad oil, such as soybean oil, may exhibit complete emulsion break after being frozen for about 4 days.
In addition to freeze-thaw stability, the invention provides a reduced calorie spoonable dressing which employs EPG as a replacement for all or some of blended salad oil in the mayonnaise. The dressing comprising EPG has similar organoleptic characteristics as full fat dressing. The organoleptic qualities of the invention are significantly better than can be achieved with carbohydrate-based fat extenders or replacers.
In order for the fatty acid compositions of the invention to function effectively as reduced calorie substitutes for blended salad oils which are suitable for use in spoonable dressings, it is essential that the organoleptic qualities of the EPG mimic as closely as possible the organoleptic qualities of the replaced fat. For spoonable dressings, it is essential that the EPG have organoleptic properties similar to the organoleptic properties of the blended salad oil that is replaced by the EPG. The EPG must additionally have physical properties (e.g. viscosity, melting point, heat stability, thermal conductivity, etc.) similar to the blended salad oil.
Blended salad oils used in preparation of conventional spoonable dressings are generally lipid based vegetable oils, such as soybean oil, although other types and combination of oils can be used. The blended salad oil is combined with other ingredients to form an emulsion. When a conventional dressing is frozen and allowed to thaw, the blended salad oil breaks from the emulsion resulting in product separation. As will be explained in more detail below, it has now been unexpectedly found that when the propoxylation number and fatty acid chain length and unsaturation level are carefully controlled such that the propoxylation numbers of the EPG is from about 3 to about 16 and the EPG compositions either have a FACN:DU Ratio of less than about 120, preferably less than about 90 or a FACN:PO Ratio less than about 6, preferably less than about 5, the dressing will have freeze-thaw stability, significantly superior compared to conventional mayonnaise.
Substitution of such EPG compositions for the blended salad oil also unexpectedly results in a spoonable dressing with superior flavor, taste and texture compared to dressings prepared with the carbohydrate based replacements known in the art. The spoonable dressings comprising the EPG unexpectedly possess the same organoleptic character of full-fat products.
The dressings made with EPG have freeze-thaw stability, meaning that the emulsion does not experience complete break upon thawing after being frozen for a continuous period of time. Replacement of larger amounts of blended salad oil with EPG, results in better freeze-thaw characteristics. For example, replacement of about 40 weight percent of the blended salad oil with EPG results in a dressing with freeze-thaw stability, with only small free water droplets observed when the dressing is frozen for about 96 hours with complete emulsion break occurring only after about 504 hours of freezing. When the amount of blended salad oil replaced by EPG is increased to 80 weight percent, no effect on the dressing is observed when the dressing is frozen for about 504 hours. Freeze-thaw stability is generally experienced when about 25 weight percent or more of the conventional blended salad oil is replaced with the EPG, particularly EPG with propoxylation numbers from about 3 to about 16 and the specific FACN:DU Ratio or FACN:PO Ratio discussed herein.
The reason for freeze-thaw stability when all or some of the conventional blended salad oil is replaced with these EPG compositions is not completely understood and the inventors wish not to be bound by any particular theory. The properties of EPG that arise from the particular formulations whereby the propoxylation numbers range from about 3 to about 16 and the FACN:DU Ratio is less than about 120 or the FACN:PO Ratio is less than about 6 may effect the freeze-thaw stability. EPGs with propoxylation numbers less than about 3 and different fatty acid ratios act more like conventional vegetable oil and loose emulsifying properties. EPG compositions with propoxylation numbers greater than about 16 and different fatty acid ratios become too soft for use and creation of stable dressings. EPG compositions with from about 3 to about 16 oxypropylene units per unit of glycerin and the fatty acid ratios discussed herein have sufficient polarity and hydrophilicity to assist with better interaction with water making the number of oxypropylene groups and fatty acid ratios critical to water interaction and emulsion stability, particularly freeze-thaw stability. Thus, the unique physical properties of these EPG compositions results in a more stable dressing thus providing the freeze-thaw stability.
Another theory, particularly pertinent where the EPG is used as a partial fat replacement, is that the oxypropylene groups effect the ability of the fat to crystallize in typical fashion thus resulting in better thermal stability, e.g. freeze-thaw stability. The propoxylation number is an average of the number of oxypropylene groups. For example, an EPG having an average propoxylation number of 5, e.g. EPG-05, can have from 3 to 8 oxypropylene groups per molecule. Thus, EPG has a greater variation in the overall chain length than conventional fats, which helps prevent crystallization growth at lower temperatures thereby permitting for maintenance of the emulsion when the spoonable dressings are frozen.
The EPG compositions of this invention contain glyceryl residues, oxypropylene units, and fatty acid acyl 
groups. Typically, the compositions are mixtures of individual EPG compositions which may differ from each other in degree of propoxylation and acyl group composition. The glyceryl residue may have the generic structure 
and is derived from glycerin 
or a glycerin equivalent. The oxypropylene units are generally interspersed between glyceryl residues and the acyl groups and have the structure 
Typically, more than one oxypropylene unit may be present between an oxygen of an individual glyceryl residue and an acyl group such that a polyoxypropylene unit is created. However, a single xe2x80x9cbranchxe2x80x9d or xe2x80x9carmxe2x80x9d of the fatty acid-esterified propoxylated glycerin may contain only one oxypropylene unit. Certain of the acyl groups may be attached directly to the glyceryl residue, without any intervening oxypropylene units, although an average of at least about 3 oxypropylene units per glyceryl residue must be present in the overall composition. The average number of oxypropylene units per unit of glycerin in the EPG composition useful for making the reduced calorie dressings with freeze-thaw stability is from about 3 to about 16 and can be from about 5 to about 14. The presence of oxypropylene units is critical, in addition to the FACN:DU Ratio or FACN:PO Ratio, as the oxypropylene units help to lower the melting point of the compositions thereby improving the mouthfeel and melting characteristics as compared to analogous compositions not containing oxypropylene units. EPG compositions with propoxylation numbers from about 3 to about 16 are suitable for the invention as this results in a solid fat index appropriate for providing the dressings with the mouthfeel and organoleptic properties of conventional dressings made with blended salad oil and provides for a dressing with freeze-thaw stability.
In order to maximize the resistance of the composition towards pancreatic lipase enzyme-catalyzed hydrolysis, the oxypropylene units adjacent to the acyl groups should be oriented such that secondary rather than primary ester linkages are created. That is, the methyl group should be located on the carbon atom attached to the oxygen atom forming part of the ester linkage as follows: 
Preferably, at least about 80 percent of the ester linkages in the overall composition are secondary. Most preferably, at least about 95 percent of the ester linkages are secondary. However, the secondary ester content can be less than about 80 percent without adversely affecting the organoleptic properties of the invention.
It is desirable for the fatty acid-esterified propoxylated glycerin composition to be substantially esterified such that it has an average of at least about 2.5 (more preferably, at least about 2.9) fatty acid acyl groups per equivalent of glycerin. The extent of esterification may be readily determined by conventional analytical methods such as hydroxyl number.
The structure of the composition preferably is such that the composition has a porcine pancreatic lipase hydrolysis rate of less than about 10 percent, and preferably less than about 1 percent, as compared to an olive oil standard. Methods of measuring porcine pancreatic lipase hydrolysis rate are described in White.
The average number of oxypropylene units in the EPG must not be so low as to result in a high proportion of the acyl groups being attached directly to glyceryl residues since such directly attached acyl groups will be nearly as susceptible to enzymatic cleavage as the acyl groups in a conventional fully digestible triglyceride, thus reducing the usefulness of the composition as a low calorie fat substitute.
Suitable EPGs may be prepared using either fatty acids or fatty acid derivatives such as fatty acid esters, fatty acid halides, or fatty acid anhydrides. Generally speaking, C12-C24 linear fatty acids and their derivatives are preferred for use as starting materials for preparing the EPGs. Specific illustrative fatty acids for use as this component of the EPG compositions include, but are not limited to, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, arachidonic acid, behenic acid, eicosapentaenoic acid, docosahexenoic acid, lignoceric acid or mixtures thereof. Minor amounts of branched and/or shorter chain fatty acids may also be utilized. Preferably, linear monocarboxylic acids containing from 0 to about 5 double bonds are employed.
The total number of fatty acid acyl group carbons per equivalent of glycerin in the fatty acid-esterified propoxylated glycerin compositions of the invention (i.e. the total fatty acid carbon number (FACN)) may be readily calculated from a knowledge of the fatty acid acyl group content (i.e., the chemical structures and relative proportions of the fatty acids used to prepare the compositions). The following formula may be used to calculate this total number (Nt) for an EPG composition prepared using fatty acids A and B:       N    t    =                    moles        ⁢                  xe2x80x83                ⁢        A        xc3x97                  no          .                      xe2x80x83                    ⁢          carbons                ⁢                  xe2x80x83                ⁢        in        ⁢                  xe2x80x83                ⁢        A                    moles        ⁢                  xe2x80x83                ⁢        propoxylated        ⁢                  xe2x80x83                ⁢        glycerin              +                  moles        ⁢                  xe2x80x83                ⁢        B        xc3x97                  no          .                      xe2x80x83                    ⁢          carbons                ⁢                  xe2x80x83                ⁢        in        ⁢                  xe2x80x83                ⁢        B                    moles        ⁢                  xe2x80x83                ⁢        propoxylated        ⁢                  xe2x80x83                ⁢        glycerin            
For example, a composition prepared by reacting a mixture of 1.5 moles of stearic acid (a C18 fatty acid) and 1.5 moles of eicosanoic acid (a C20 fatty acid) with 1 mole of propoxylated glycerin containing an average of 7 oxypropylene units per glycerin will have a total of 57 fatty acid acyl carbons per equivalent of glycerin.
The degree of unsaturation (DU) can be readily calculated from data obtained on analysis of fatty acid composition. The weight percent of each unsaturated fatty acid is multiplied by the number of double bonds contained within each particular unsaturated fatty acid. These values are then added to obtain the degree of unsaturation for the EPG composition.
To minimize the available caloric content of the EPG compositions of this invention, which are employed as full or partial replacement of blended salad oil in dressing preparations, the chemical composition should be selected such that the number average molecular weight is at least about 800. More preferably, the minimum molecular weight is about 1,000; in order for the fatty acid-esterified propoxylated glycerin composition to mimic as closely as possible the physical properties of blended salad oil (such as texture, melting point, viscosity, heat stability and thermal conductivity). It is also desirable that the number average molecular weight not exceed about 2,200. Preferably, the molecular weight is below about 2,000.
EPG compositions with propoxylation numbers from about 3 to about 16, including propoxylation numbers from about 5 to about 14, are useful as full or partial replacements for lipid based fats in spoonable dressings to obtain spoonable dressings with freeze-thaw stability and reduced calories. EPG compositions having unsaturated fatty acids and a FACN:DU Ratio of less than about 120, preferably less than about 90, or having no unsaturated fatty acids and a FACN:PO Ratio of less than about 6, preferably less than about 5, are used as replacement compositions for the blended salad oil in spoonable dressings, such as mayonnaise, to make reduced calorie spoonable dressings with freeze-thaw stability.
The fatty acid-esterified propoxylated glycerin blended salad oil replacement compositions of this invention may be prepared using any suitable method. In general, the procedures described in the prior art for synthesizing other fatty acid-esterified propoxylated glycerin compositions will be appropriate for use provided that the necessary C12-C24 linear fatty acids (or precursors thereof) or fatty acid derivatives are employed in the esterification step. Such procedures are described, for example, in U.S. Pat. Nos. 4,861,613 (the White patent, referenced above) and 4,983,329, and in European Patent Publication No. 353,928, the disclosures of which are incorporated by reference herein in their entirety. Either fatty acids or fatty acid equivalents such as fatty acid esters, fatty acid halides, or fatty acid anhydrides may actually be employed in the esterification. The C12-C24 saturated linear fatty acid acyl groups may be introduced by using C12-C24 unsaturated fatty acids in the esterification step and then hydrogenating the fatty acid-esterified propoxylated glycerin composition to increase the proportion of C12-C24 saturated linear fatty acid acyl groups to the desired level. Any residual free fatty acid remaining in the composition after esterification should preferably be removed or reduced as much as possible to minimize problems with off flavor, off-odor, or storage stability.
The spoonable dressings are prepared with EPG as a full or partial replacement of conventional fat in the dressing. Freeze-thaw stability is experienced when about 25 percent or more of the blended salad oil is replaced with EPG, that is the fat component has a composition of from about 25 weight percent to 100 weight percent EPG with the balance (zero to about 75 weight percent) blended salad oil. Excellent freeze-thaw stability is experienced when about 40 percent or more of the conventional fat of the mayonnaise is replaced with EPG (e.g. between about 40 weight percent and 100 weight percent of the blended salad oil is replaced with EPG), particularly the EPG compositions described above. In this embodiment the fat component has a composition of from about 40 weight percent to 100 weight percent EPG with the balance (zero to about 60 weight percent) blended salad oil. Exemplary freeze-thaw stability is experienced when between about 80 percent and 100 percent of the conventional fat is replaced with EPG. In this embodiment the fat component has a composition of from about 80 weight percent to 100 weight percent EPG with the balance (zero to about 20 weight percent) blended salad oil. When less than about 25 percent of the conventional fat is replaced with EPG, the freeze-thaw characteristics of the dressing is similar to the full fat compositions.
In addition to the fat component comprised of the EPG, the spoonable dressings may further comprise other ingredients such as seasonings, spices and flavorings. The spoonable dressings may also include emulsifiers such as lecithin, antioxidants, dietary fibers, vitamins, bulking or bodying agents such as polydextrose or modified starch, salt and the like. A sugar alcohol such as sorbitol, xylitol, or mannitol or a reduced calorie sweetener such as saccharine, aspartame, cyclamates, sucralose, acesulfame, acesulfam-K, or the like may also be employed in combination with the EPG composition. The spoonable dressing compositions are prepared by traditional methods for making mayonnaise as would be apparent to one skilled in the art.